The present invention relates to an image forming apparatus that is applicable, for example, as a printer, a copying machine or a facsimile, and to an image forming unit used therefor.
In a conventional image forming unit of an image forming apparatus, units having a handle for carrying it easily, has been much developed. For example, JP 2-11155B discloses an image forming unit shown in FIG. 14, in which a handle 300 is formed as one unit with an image forming unit main body 301.
However, in the image forming unit having this conventional handle, since the handle is formed as one unit with the image forming unit main body, it is necessary to have a large space for containing the image forming unit in the image forming apparatus. Consequently, it is not possible to downsize the image forming apparatus.
Furthermore, in this kind of image forming apparatus, it is necessary to detect the amount of toner that remains in the image forming unit. As a technology for detecting the amount of remaining toner, for example, the technology disclosed in JP 6-317986A is well known. This publication discloses an image forming apparatus including a light transmission window on the developing device and an aperture on a developing cartridge so that a developing cartridge has a light path passing through a toner containing portion of the developing device on a line connecting a rotary unit (which is a holding member of a switching mechanism) and an outer position sandwiching the developing cartridge between the rotary unit and the outside position when a developing cartridge is positioned at the developing position. In this apparatus, the amount of toner remaining in the toner containing portion of the developing cartridge positioned at the developing position is detected by a light transmission method at the position between the rotary unit and the outer position.
Furthermore, in the image forming apparatus having this conventional means for detecting the amount of remaining toner, since the amount of remaining toner in the toner containing portion is detected by the light transmission method at a position outside of the position sandwiching the developing cartridge between the rotary unit and the outside position, the light path for detection becomes longer. As a result, the optical sensor becomes specific, which may deteriorate the accuracy.
Furthermore, as a conventional color image forming apparatus, in particular, an image forming unit used therefor, for example, one disclosed in JP 6-93141B is well known.
The following is a description of the conventional image forming unit disclosed in this publication, with reference to FIG. 15. In FIG. 15, numeral 302 denotes a photosensitive member, 303 denotes a developing roller, and 304 denotes a charger. Numeral 305 denotes a photosensitive member unit supporting the photosensitive member 302 and the charger 304 and formed into one unit with a cleaner case, and 306 denotes a developing unit supporting a developing roller and formed into one unit with a toner case. The developing unit 306 is linked rotatably to the photosensitive member unit 305 by a supporting axis 307. Numeral 308 denotes a compression spring, which is provided at the opposite side to the photosensitive member 302 while sandwiching the supporting axis 307 between the developing unit 306 and the photosensitive member unit 305. Thereby, the photosensitive member 302 and the developing roller 303 are pressed to each other and in contact with each other. The developing roller 303 is driven to be rotated by using a rotation force of the photosensitive member 302. A gear fixed to the photosensitive member 302 and a gear fixed to the developing roller 303 (both gears are not shown) are coupled with each other and driven to be rotated in the arrow directions, respectively.
In general, when such a image forming unit is attached to an electro-photographic apparatus main body, the axis center position of the photosensitive member 302 and a part of the photosensitive member unit 305 are supported firmly by the apparatus main body, and the photosensitive member 302 is driven to be rotated. Thus, images are formed.
In the formation of a color image, it is necessary to reduce unnecessary disturbance to the photosensitive member so as to improve the rotation accuracy of the photosensitive member and to bring the developing roller into light and uniform contact with the photosensitive member, thus to form a image with less unevenness in color or thickness of the image.
However, in the above-mentioned conventional image forming unit, the unevenness in rotation is transferred easily to the photosensitive member. Furthermore, the rotation driving force applying to the developing roller works as a pressing power with respect to the photosensitive member. As a result, the contact pressure of both rollers is uneven, and thus the unevenness in colors or thickness of the image tends to occur.
It is an object of the present invention to provide an image forming unit having a handle and a compact size with a smaller containing space needed and an image forming apparatus using this image forming unit. Furthermore, it is another object of the present invention to provide an image forming unit capable of detecting the amount of toner remaining in a toner containing portion without deteriorating the detection accuracy and having a simple structure, and an image forming apparatus using this image forming unit. Furthermore, it is a further object of the present invention to provide an image forming unit and an image forming apparatus using this image forming unit, which do not tend to provide disturbance to the rotation of the photosensitive member; keep the contact pressure between the developing roller and the photosensitive member small and uniform; and are capable of forming a high quality image without unevenness in colors or thickness of the image.
In order to attain the above-mentioned object, a first configuration of an image forming unit according to the present invention includes an image forming unit main body having an image forming means, and a handle provided at the image forming unit main body so that it is capable of taking a holdable posture in which a user can hold the handle and a non-holdable posture in which a user cannot hold the handle, and is urged toward the non-holdable posture constantly by its elasticity. According to the first configuration of the image forming unit, it is possible to attain an image forming unit equipped with a handle and having a compact size with a smaller containing space required as compared with conventional units.
It is preferable in the first configuration of the image forming unit according to the present invention that the handle is made of an elastic plate having elongated holes at both ends thereof, is attached to an attachment surface of the image forming unit main body through the elongated hole by an anchoring member, and is capable of taking a non-holdable posture in which the handle is in contact with or close to the attachment surface and a holdable posture in which at least one part of the handle is separated from the attachment surface. With such a preferred configuration, it is possible to realize an image forming unit having a handle with a simple structure and inexpensively.
Furthermore, it is preferable in the first configuration of the image forming unit according to the present invention that the image forming unit is used for the image forming apparatus in which a plurality of image forming units are arranged rotatably in a vertical plane, and the plurality of image forming units are shifted sequentially to the image forming position so as to form images, wherein the handle is provided on the outer periphery of the rotation surface of the image forming unit main body. With such a preferred configuration, it is possible to attach/detach the image forming unit to/from the image forming apparatus easily. In this case, it is further preferable that the handle is urged toward the non-holdable posture by an elasticity that is stronger than a self-weight by which the handle is urged toward the holdable posture. With such a preferred configuration, it is possible to prevent the handle from taking the holdable posture when it comes to the lowermost place. In this case, it is still further preferable that the image forming unit includes a photosensitive member and a developing device and that the photosensitive member is exposed to the outer periphery of the rotation surface of the image forming unit main body. With such a preferred configuration, it is possible to transfer a toner image on the photosensitive member to the recording paper, easily. In this case, it is further preferable that the handle in its non-holdable posture is present inside the rotation track surface of the photosensitive member, and the handle in its holdable posture is present outside the rotation track surface of the photosensitive member. With such a preferred configuration, when the image forming unit is rotated in the image forming apparatus, the handle avoids contact with the transfer means without the need for additional complex operation.
It is further preferable that the image forming unit of the first configuration according to the present invention includes a photosensitive member unit that supports the photosensitive member and a developing unit that supports the developing device and that the handle is provided at the side of the developing unit. With such a preferred configuration, since the handle is provided at the side of the developing unit containing heavier parts such as a developing device, etc., it is possible to balance the image forming unit when it is suspended by holding the handle. Furthermore, by providing the handle at the side of the developing unit, it is possible to secure a sufficient space for placing the handle.
According to the first configuration of the image forming apparatus according to the present invention, the image forming apparatus including a unit-rotating member that supports a plurality of image forming units in a vertical plane rotatably, and forming images by shifting the plurality of image forming units sequentially to the image forming position, wherein the image forming unit includes an image forming unit main body having an image forming means, and a handle provided at the image forming unit main body so that it is capable of taking a holdable posture in which a user can hold the handle and a non-holdable posture in which a user cannot hold the handle, and is urged toward the non-holdable posture constantly by its elasticity.
It is preferable that the first configuration of the image forming apparatus according to the present invention includes an opening/closing door for allowing attaching/detaching of the image forming unit to/from the upper part of the unit-rotating member, wherein the opening/closing door is capable of pressing, in its holdable posture, the handle of the image forming unit installed to the unit-rotating member. With such a preferred configuration, even if a user forgets to put the handle in the non-holdable posture, when the image forming unit is replaced with a new unit, by only closing the opening/closing door, the handle can be put in the non-holdable posture. Furthermore, in this case, it is preferable that the opening/closing door is provided with a protruding portion capable of being brought into contact with the handle of the image forming unit in its holdable posture.
Furthermore, according to the second configuration of the image forming apparatus of the present invention, the image forming apparatus includes a unit-rotating member that supports a plurality of image forming units in a vertical plane rotatably, and forming images by shifting the plurality of image forming units sequentially to the image forming position, wherein the image forming unit comprises an image forming unit main body, a photosensitive member exposed to the outer periphery of the rotation surface of the image forming unit main body, a handle provided at the image forming unit main body, and the handle of the image forming unit at the position where the image forming unit is replaced with a new unit in the unit-rotating member, is arranged farther from a front side of the image forming apparatus than the photosensitive member. According to the second configuration of the image forming apparatus, when the image forming unit is replaced with a new unit, it is possible reliably to prevent the operator""s finger from touching the exposed photosensitive member.
Furthermore, according to the third configuration of the image forming apparatus of the preset invention, the image forming apparatus includes a unit-rotating member that supports a plurality of image forming units in a vertical plane rotatably, and forming images by shifting the plurality of image forming units sequentially to the image forming position, wherein the image forming unit comprises a photosensitive member unit that supports the photosensitive member, a developing unit that supports the developing device, and a handle; the photosensitive member is exposed to the outer periphery of the rotation surface of a photosensitive member unit main body; in the image forming unit at the position where the image forming unit is replaced with a new unit in the unit-rotating member, the photosensitive member unit and the developing unit are arranged in this order from the front side of the image forming apparatus; and the handle is provided at the side of the developing unit. According to the third configuration of the image forming apparatus, it is possible to locate the handle of the image forming unit in the unit-rotating member at a replacement position where the image forming unit is replaced with a new unit farther from the front side of the image forming apparatus than the photosensitive member. As a result, when the image forming unit is replaced with a new unit, it is possible reliably to prevent the operator""s finger from touching the exposed photosensitive member.
Furthermore, it is preferable in the second or third configuration of the image forming apparatus according to the present invention that the replacement of the image forming unit from the rear side of the image forming apparatus is suppressed. With such a preferred configuration, it is possible reliably to prevent the operator""s finger from touching the photosensitive member. In this case, it is still further preferable that the image forming apparatus includes an opening/closing door for attaching/detaching the image forming unit to/from the upper part of the unit-rotating member, thereby regulating the replacement of the image forming unit from the rear side of the image forming apparatus.
According to the second configuration of the image forming unit of the present invention, an image forming unit is used for the image forming apparatus in which a plurality of image forming units are arranged rotatably in a vertical plane, and the plurality of image forming units are shifted sequentially to the image forming position, wherein a translucent detection window for detecting the amount of remaining toner is provided on the periphery of the rotation surface of the image forming unit main body that communicates to a toner hopper. According to the second configuration of the image forming unit, a translucent detection window for detecting the remaining toner is provided on the outer periphery of the rotation surface of the image forming unit main body that communicates to the toner hopper. Therefore, by arranging a detection member such as a light emitting element, a light receiving element, or the like, in the vicinity of the detection window, it is possible to detect the amount of remaining toner, thus to shorten the light path for detection. As a result, it is possible to enhance the accuracy in detecting the amount of remaining toner. Furthermore, the translucent detection window is exposed to the outside of the image forming unit main body, it is possible to check visibly the amount of remaining toner after taking out the image forming unit from the image forming apparatus main body.
Furthermore, it is preferable in the second configuration of the image forming unit according to the present invention that the detection window is located at the corner on the periphery of the rotation surface of the image forming unit main body. With such a preferred configuration, since the detection window is located at the bottom surface of the toner hopper, it is possible to detect only a small amount of toner easily.
Furthermore, it is preferable in the second configuration of the image forming unit according to the present invention that the detection window is provided in a cavity formed in the toner hopper, and has a pair of opposed side faces, further comprising reflection planes refracting light for detecting the amount of remaining toner, the reflection planes being provided in the vicinity of the pair of side faces. With such a preferred configuration, it is not necessary to arrange a detection member such as a light emitting element, a light-receiving element, etc., and it is possible to make the light path for detection relatively short.
Furthermore, it is preferable that the second configuration of the image forming unit according to the present invention includes a cleaning member for cleaning the detection window. With such a preferred configuration, it is possible to enhance the accuracy in detecting the amount of remaining toner by appropriately cleaning the detection window.
According to the fourth configuration of the image forming apparatus according to present invention, an image forming apparatus includes a unit rotating member that supports a plurality of image forming units in a vertical plane rotatably, and forming images by shifting the plurality of image forming units sequentially to the image forming position; wherein a translucent detection window for detecting the amount of remaining toner is provided on the periphery of the rotation surface of the image forming unit main body that communicates with a toner hopper.
It is preferable in the fourth configuration of the image forming apparatus according to the present invention that the detection window is located at the corner on the periphery of the rotation surface of the image forming unit main body.
Furthermore, it is preferable in the fourth configuration of the image forming apparatus according to the present invention that the detection window is provided in a cavity formed in the toner hopper, and has a pair of opposed side faces, further comprising reflection planes refracting light for detecting the amount of remaining toner, the reflection planes being provided in the vicinity of the pair of side faces. Furthermore, in this case, it is preferable that a detection means that emits/receives light for detecting the amount of remaining toner is provided facing the periphery of the rotation surface of the image forming unit main body.
Furthermore, it is preferable in the fourth configuration of the image forming apparatus according to the present invention that the detection of the amount of remaining toner is performed at a different position from the image forming position. With such a preferred configuration, it is possible to arrange the detection means that emits/receives light for detection of the amount of remaining toner. Furthermore, in this case, it is preferable that the detection of the amount of remaining toner is performed when the detection window is located at a lower place than the horizontal line including the rotation center of the unit-rotating member. With such a preferred configuration, it is possible to detect only a small amount toner. Furthermore, in this case, it is preferable that the detection of the amount of remaining toner is performed when the image forming unit is located at the opposite side to the image forming position. Furthermore, in this case, it is preferable that a cleaning member for cleaning the detection window is provided, and the cleaning of the detection window is performed only at the image forming position. With such a preferred configuration, it is not necessary to provide a mechanism for driving the cleaning member at several positions, thus simplifying the structure of the image forming apparatus.
Furthermore, it is preferable in the second configuration of the image forming apparatus according to the present invention that the amount of remaining toner of the image forming unit for one color is detected several times while the unit-rotating member rotates several times thus to obtain the detected results, and the amount of the remaining toner is determined based on the detected results. With such a preferred configuration, it is possible to reduce the detection error and to detect the amount of the remaining toner precisely.
Furthermore, according to the third configuration of the image forming unit according to the present invention, an image forming unit includes a photosensitive member unit having a photosensitive member on the surface of which a electrostatic latent image is formed, and a developing unit which has a developing agent, a developing roller supporting the developing agent at the developing region, and a driving transmitting means for rotating the developing roller, and which develops the electrostatic latent image to be a manifest image, wherein the developing unit is supported by the photosensitive member unit rockably, the point of application, which transmits the rotation force to the developing unit, is provided in the vicinity of the rocking center axis of the photosensitive member unit and the developing unit. With the third configuration of the image forming unit, the developing unit is driven to be rotated by the force that transmits a rotation force to the developing unit, and the developing roller is not pressed onto the photosensitive member and the pressing power that is set when the developing roller is not rotated can be maintained. Therefore, it is possible to bring the developing roller into contact with the photosensitive member constantly and stably.
Furthermore, it is preferable in the third configuration of the image forming unit according to the present invention that a driving force for rotating the developing roller is applied from the outside of the image forming unit. With such a preferred configuration, the photosensitive member is not subjected to a load fluctuation as the photosensitive member drives the developing roller. Moreover, since the contact pressure of the developing roller to the photosensitive member can be set to be small, the photosensitive member is not susceptible to the disturbance from the developing roller, whereby the stable rotation can be secured. Furthermore, in this case, it is preferable that the developing roller is in contact with the photosensitive member, thereby developing an electrostatic latent image to be a manifest image. Furthermore, in this case, it is preferable that the developing unit is supported by the photosensitive member unit rockably at the driving side of the developing unit, and the relative position between the photosensitive member of the photosensitive member unit and the developing roller is determined by a sliding guide provided at the photosensitive member unit at the opposite side to the driving side of the developing unit. With such a preferred configuration, it is possible to maintain the state in which the photosensitive member is in contact with the developing roller evenly over the entire surface regardless of the torsion, etc., of the box. Furthermore, in this case, it is preferable that the driven gear that is driven directly from the outside of the image forming unit among the driving force transmitting means for rotating the developing roller is supported rockably with the rotating axis of the developing roller as a center. With such a preferred configuration, it is possible automatically to couple a carriage, to which the image forming unit is attached, at the side of the main body to a developing driving main body gear at the side of the main body by only rotating the carriage. Furthermore, in this case, it is preferable that the image forming unit further includes a rocking member that supports the driven gear rockably, wherein the rocking member engages an anchoring portion provided at the image forming unit when the rotation force is transmitted from the outside of the image forming unit to the developing roller. With such a preferred configuration, since the rotation moment around the engagement portion is not applied from the outside of the developing unit, it is possible to bring the photosensitive member into contact with the developing roller in a stable state. Furthermore, in this case, it is preferable that the image forming unit includes anchoring portions provided at both ends of the photosensitive member and supported by the apparatus main body, and a rotation anchoring portion provided at the driving force transmitting side of the developing unit and positioning the rotation position around the rotation axis of the photosensitive member. With such a preferred configuration, since the image forming unit is supported by the apparatus main body at three points, i.e. at the engagement portion at both ends of the rotation axis of the photosensitive member and at the rotation anchoring portion, it is possible to position the photosensitive member with respect to the apparatus main body reliably. At the same time, it is possible to solve the problem that it is difficult to bring the photosensitive member into contact with the developing roller reliably because the image forming unit is subjected to a developing driving force and the unit is twisted. Furthermore, in this case, it is preferable that the rotation anchoring portion is provided in the photosensitive unit. With such a preferred configuration, since the rotation force is supported only by the photosensitive member unit, the state in which the photosensitive member is in contact with the developing roller is not affected. Furthermore, in this case, it is preferable that the rotation anchoring portion is a supporting axis that supports the developing unit rockably or a receiving portion of the supporting axis. With such a preferred configuration, at the place where the outside power is applied to the image forming unit, the carriage at the side of the main body supports the image forming unit, the excess twisting power does not occur in the image forming unit.
Furthermore, according to the fifth configuration of the image forming apparatus, an image forming apparatus includes a plurality of image forming units combining a developing device and a photosensitive member for each color; an image forming unit transmitting means for switching the image forming units by sequentially shifting the image forming unit for each color between an image forming position and other waiting positions; a positioning means for positioning the photosensitive member at the image forming position; an exposing means for exposing the photosensitive member located at the image forming position; a transfer means for transferring sequentially the toner images of many colors, which are formed on the photosensitive member at the image forming position by the developing device, to form a toner image in which toner images of many colors are overlapped on the photosensitive member; and a rotation driving means for rotating the photosensitive member and the transfer means, wherein an image forming unit according to the present invention is used as the image forming unit. According to the fifth configuration of the image forming apparatus, it is possible to position the photosensitive member reliably by a simple structure and further to form a high quality and stable image capable of securing the uniform development by pressing lightly.